Respiratory Flashcards
What are three respiratory tract defence against inhaled particles?
Defending against inhaled particles:
Filters particles from inhaled air
Prevents particles contacting and damaging inhaled surfaces
Removal of particles
What are the 6 airway defence mechanisms?
Aerodynamic filtration
Mucociliary escalator
Antibacterial agents
IgA
Protective reflexes
Leucocytes
How does the mechanism of aerodynamic filtration work?
Coiled turbinates leads to turbulence causing particles above 10um to impact on the airway mucosa (think workshop filters)
Bronchi filter anything over 3um
Particles 1-5um are deposited in the bronchioles and alevoli
Describe the process of the mucociliary escalator
Layer of mucous then cilia surrounded by aqeous solution allowing them to beat
Goblet cells produce mucuous
Traps and transports particles from airways to pharynx
Acts as a physical barrier, prevents dehydration, dilutes soluble gases and contains anti-bacterials
What two anti-bacterials does mucus contain?
Lysozome- bacteriolytic protein that hydrolyzes peptidoglycan
Lactoferrin- Fe-binding protein synthesised by neutrophils and ep cell, retarding bacterial and fungal growth
What factors affect mucocilliary carpet function?
Changes in viscocity of mucous- temperature, dehydration, inflammation
Injury to epithelium- trauma, infections, irritation
What can cause respiratory epithelial metaplasia?
Secondary to chronic irritation- bronchitis
Ciliated columnar to stratified squamous
What does IgA do in airways?
transports through mucus and precipitates antigens for phagocytosis
What are the protective reflexes?
Coughing, sneezing
What are the different alveolar defences?
Macrophages- alveolar, intersitial, intravascular
Phagocytose- particles and agents
Recruit neutrophils
Coordinate inflammation
Ascend mucocilary escalator
What agents cause cat flu and what does it cause?
Feline herpes virus and feline calicivirus
Causes conjunctivitis, rhinits
Conjuncitivis can lead to pus which is a secondary bacterial product- virus damages epithelial cells (impairs clearence) causing secondary bacterial infection
What are 3 examples of developmental abnormalities of the upper airways and their effects?
Cleft palate- failure of two palatine shelves to close, can cause aspiration of the food- aspiration pneumonia
Guttural pouch tympany- nasopharyngeal opening defect- air in guttural pouch leads to dyspnoea and dysphagia (difficulty swallowing) and aspiration pneumonia
Brachiocephalic airway syndrome- combination of anatomical problems- stenotic nares, everted laryngeal saccules, elongated soft palate, causes airway obstruction- cyanosis and syncope (fainting)
What is epistaxis and what are the sources and potential causes?
Epistaxis is bleeding from the nose
Sources- upper airways and lower respiratory tract
Causes- inflammation, infection, trauma, neoplasia, clotting defects
What ate the 5 typical signs of inflammation?
Redness- vasodilation and congestion/haemorrhage
Swelling- infiltration of cells and fluid
Heat- increased blood supply
Pain- due to compression of tissue sensors
Loss of function- depends on site
What is the difference between actue and chronic inflammation?
In both acute and chronic there is the same processes- serous, catarrhal, purulent but in acute there is healing and resolution where is in chronic the insult persists and causes pathological changes
How is inflammation classified?
By the type of exudate
Serous- clear watery discharge, mild, increased production from mucoserous glands, hyperaemia and oedema
Catarrhal- viscous mucoid, increased mucoserosal secretions, minor numbers of inflammatory cells
Fibrinous- thick, fibrinous and haemorrhagic- many inflammatory cells and haemorrhagic discharge, increased vascular permeability with or without necrosis
Purulent- thick, white, green, brown- many inflammatory cells, especially neutrophils and cell debris
What pathological changes does chronic inflammation cause in the respiratory tract?
Causes mucosal hyperplasia- goblet cell hyperplasia, seromucous gland hyperplasia
Epithelial metaplasia
Chronic inflammatory cells- macrophages, lymphocytes
Fibroplasia
What can be found secondary to chronic inflammation in horses and cats?
Polyps
Seen in horses and cats
Cat- arise in the auditory tube or tympanic bulla extend into pharnx or along ear canal
What are some common causes of airway inflammation?
Pollen
Dust
Fomites
Foreign bodies
Parasites
Infectious agents
What viral agents are associated with inflammation of the URT?
BEEF FCCC
Bovine herpes virus 1 (IBR)
Equine herpes virus 1/4
Equine influenza virus
Feline herpes virus 1- cat flu
Feline calicivirus- cat flu
Canine distemper virus
Canine adenovirus 2- kennel cough
Canine parainfluenza virus- kennel cough
What is needed for an infectious disease?
Julian’s favourite phrase
An infectious disease is an aetiological agent, on a susceptible host, in a favourite environment
What is an example of a viral URT infection- give a brief overview
IBR- bovine herpes virus 1
Infection of nasal and conjunctiva epithelial cells leadind to serous or catarrhal exudate
Can spread throughout respiratory tree and damage mucociliary escalator leading to impaired defenses
Secondary bacterial infection can cause influx of neutrophils and putulent discharge- usually resolved
What are two examples of bacterial URT infections?
Streptococcus equi in horses- strangles
Pasteurella multocida in pigs- atrophic rhinitis
Briefly describe a strangles and atrophic rhinitis infection
Strangles- streptococcus equi colonises nasopharyngeal mucosa, serous to purulent, spreads to lymph nodes, abscesses within parotid lymph node can rupture, can rupture into guttural pouch
Atrophic rhinitis- pigs- pasturella multocida, types A and D and calcium imbalende and bad genetics, causes atrophy and distortion of turbinates
What type of infection is aspergillus fumifatis?
What species does it affect?
What can predispose it?
What type of inflammation does it cause?
Fungal infection- URT
Affects dogs, horses and birds
Usually immunosuppressed animals
Fibronecrotic/granulomatous inflammation and bone lysis due to cytolytic enzymes- can cause guttural pouch mycosis
What are the complications of gutteral pouch mycosis?
Damage to cranial nerves- paralysis of facial muscles, tongue, pharynx, larynx
Erosion of blood vessels- internal carotid- could be fatal
In what age of dogs is URT neoplasia more common?
What kind of tumour is it 80% of the time?
What dog breeds have an increased risk?
Most common in middle-aged to elderly animals
>80% malignant
Breeds- airdales, bassets, OESD, shetland sheep dog, german short hair pointer
What are the different tissues of the URT that can become neoplastic and what is the neoplasia called?
Epithelial tissues-
lining- squamous cell carcinoma,
glands- adenocarcinoma
Mesenchymal-
cartilage- chondrosarcoma
bone- osteosarcoma
connective tissue- fibrosarcoma
Lymphoid tissue- lymphoma
What are the two developmental abnormalities of the trachea and larynx and briefly describe them?
Hypoplastic trachea- decreased tracheal lumninal diameter- reduced diameter also increases the resistance. This leads to exertional dyspnoea and excercise intolerance
Tracheal collapse- dorsoventral flattening of cartilage rings, minature and toy breeds affected- causes dyspnoea depending on severity
What degenerative diseases affect the trachea and larynx?
How does it affect different species?
What can cause the degenerative disease?
What is the problem with this disease?
Laryngeal paralysis
Horses- unilateral on left side (hemiplegia-roaring), dogs bilateral
Can be inherited (huskies and bouviers) or choke chain trauma
Laryngeal paralysis leads to atrophy of the cricoarytenoid muscles and therefore failure of the arytenoid cartilages to abduct during inspiration
What can cause laryngeal oedema?
Local trauma- intubation
Irritant- smoke
Acute respiratory infections
Laryngeal chrondritis
Anaphylaxis/allergic reactions
EMERGENCY
What do these three photos show?
They all show tracheitis/laryngitis
A) mucosal hyperaemia, oedema, ulceration with a
serous or catarrhal exudate
B) Fibrinous inflammation- severe damage to mucosa and blood vessels
C) Necrotic inflammation- extensive necrosis danger or airway obstruction and inhalation of debris
What can cause tracheitis and laryngitis?
Infectious agents- IBR, Influenza, Feline and equine herpes, bordatella
Trauma
Irrirants
Foreign bodies
Parasites
Neoplasia- rare
What causes calf diptheria?
What can cause the calf to die?
Opportunistic infection of fusobacterium necrophorum seccondary to mucosal dammage
Ulcerative necrosis to larynx- death tue to toxaemia and asphyxiation
What does this image show?
Oslerus osleri (Filaroides osleri) - dog
What different neoplasia could affect the trachea?
Lining epithelium- squamous cell carcinoma
Cartilage- chondroma/sarcoma
Striated muscle- rhabdomyoma
Lymphoid tissue- lymphoma
Why are broncioloes vunerable to insult?
Lack supporting cartilage
Have very few cilia and mucous- poor mucociliary defenses
Has clara cells which produce reactive metabolites
Neutrophils and macrophages on escalator from alveoli release radicals which may damage bronchioles
What can cause bronchitis/bronchiolitis?
Infectious agents- extension of upper or lower
Irritants
Allergens
Foreign bodies
Parasites
What is the difference between trachea inflammation and bronchiolitis/bronchitis?
Severe inflammtion can cause bronchiolitis obliterans
What is bronchiolitis obliterans and how does it occur?
The formation of a polyp which is then a permanent obstructive lesion in bronchiolar lumen
Purulent exudate and inflammation
Damage to the epithelium and exudate binds to basement membrane
WBCs penetrate and resolve and results in fibroblasts
Fibroblats from a polyp which is covered by epithelium
What are the effects of bronchitis and bronchiolitis?
Bronchial gland hyperplasia- increased mucus production
Epithelial hyperplasia- }
Smooth muscle hyperplasia- } thickening of mucosa
Inflammatory cells and fibrosis- }
What can cause bronchiolitis obliterans?
Chronic or repeated bacterial infections
Parasitic disease
Allergic disease
Why does chronic broncitis or bronchiolitis result in increased mucus secretion?
Bronchial goblet cell hyperplasia
Bronchial gland hyperplasia
Goblet cell metaplasia in bronchioles
Increasing mucus production
How can you tell this animal has had chronic bronchiolitis?
Hyperplasia of goblet cells- top arrows
Hyperplasia of bronchial gland- bottom arrows
How is chronic inflammation of bronchi/bronchioles presented clinically?
Dyspnoea/ Cough
Increased respiratory noise
Collapse/over inflation of lung
Reduced blood oxygenation
What is bronchiectesis?
Obstruction of the lumen by exuadate
Necrosis of the bronchial wall
Can cause permanent dilation of the bronchus
What does a successfull infection of cattle lung worm lead to and how?
Larval migration through the alveoli can cause acute pneumonia and blockage of bronchioles with exudate
Adult worms in the bronchi cause irritation and mucus production, thickened mucosa and chronic bronchitis
Airway obstruction leads to wedges of collapsed lung- cough dyspnoea
What is RAO, what is it alternatively referred to as?
Recurrent Airway Obstruction disease
AKA Heaves
What is ROA and what is most severly affected?
What does it cause?
What are the clinical signs?
Astma-like condition- type 3 hypersensitivity to inhaled allergens in mould of hay
Bronhioles most severly affected
Causes- increased mucus, mucosal thickening, peribronchial fibrosis, bronchospasm
Clinical signs- cough, mucopurulent exudate, excercise tolerant, forecul expiration, abdominal muscle hypertrophy
Which species has poor collateral ventilation?
Cattle
Degree varies in species?
What seperates lobules in the lungs and how does it vary between species?
What is the relevance of this
Lobules are seperated by septa
Cattle, pigs and sheep have thick complete septa
Horses have incomplete thick septa
Cats, dogs, rabbits and rodents have no distinct septa
Septa can prevent the spread of disease
How common are developmental abnormalities of the lung parenchyma?
Name 3 examples?
Generally very rare
Congenital melanosis
Agenesis of one or more lung lobes
Ectopic lung tissue
What is atelectasis and what can cause it?
Incomplete distension of the lung
Causes-
Complete internal obstruction
External compression of airway/lung
Pneumothorax- partial pressure v elastic recoil
Recumbancy in LA -hypostatic atelectasis
Defective surfactant production- neonates
What is emphysema what causes it?
Emphysema is over inflation of the lungs
Causes-
Forcer respiratory efforts- pneumonia
Obstructive airway disease- partial
How does partial bronchiole obstruction cause emphysma?
Lobule remains partially expanded therefore on next inspiration the lung will over inflate
What is interstitial emphysema?
Trapped air- breaks alveolar wall and enters intersitium and septa
What are the consequences of empysema?
Loss of lung elasticity- increased dead space
Loss of pulmonary capillaries
Fibrosis of remaining alveolar walls- inhibits gas exchange, reduces compliance
What circulatory disturbances can occur in the lung parenchyma?
Pulmonary oedema
Pulmonary embolism
Pulmonary haemorrhage
What does pulmonary oedema cause in the animal?
Dyspnoea- tachypnoea
Hypoxia- cyanosis if severe
Cough- moist
Why is it unusual for alveoli to flood and therefore what must occur for pulmonart oedema?
Alveolar is less permeable then capillary
Damage must have occured of increased interstitial fluid
What can the damage to alveoli that causes oedeama be?
Infectious agents
Toxins
Irritants
What does this of lung show?
Eosinophillic homogenous material diffuselly present throughout the alveoli
Oedema
Other then damage- what causes pulmonary oedema?
Increased hydrostatic pressure- inflammaiton, passive congestion, circulatory overload (renal failure)
Increased capillary permeability- endothelial damage by toxins, shock, inflammation
Reduced capillary osmotic pressure- hyperproteinaemia, over transfusion
Reduced drainage of interstitial fluid
What can be used to treat pulmonary oedema?
Diurretics to treat
What can be a pulmonary embolism?
Thromboemboli
Tumour cells- metastases
Fat
Air
Good site as fine capillary network and good blood supply
Effect depends on nature of embolism
What does this image show?
Infarction- usually requires blockage of a mjore vessel
Describe this image of lung parenchyma
What are common causes of this?
Wedge or cone shaped area of haemoglobin and necrosis due to infarction
Common sources- right heart bacterial endocarditis, joint/navel infections, liver abscesses
What do different sources of thromboembolism cause?
Sterile- fibrninolytic breakdown, fibrotic scarring
Infected thromboemboli- vasculitis, thrombosis, abscess
What are the different causes of pulmonary haemorrhage?
Pulmonary thromboembolism
Trauma
Inflammation
Abscesses/tumour (erode vessels)
What is EIPH?
Excercise induced pulmonary haemorrhage
Occurs in 75% of racehorses
What are the 4 classes of pneumonia?
Bronchopneumonia
Interstitial pneumonia
Embolic pneumonia
Granulomatous pneumonia
What classifies different pneumonias and why is it useful to know?
Distribution
Appearance
Texture
Improved diagnosis and treatment
What are common causes of bronchopneumodia?
Bacteria- mycoplasms
Aspiration of food- GI contents
Viruses
What is the distribution of bronchopneumonia and why?
Cranioventral- key
Cranioventral due to greater deposition of particles and organisms, gravitational effects, regional variations in defence mechanisms- efficiency, perfusion, ventilation
What is the difference between supprative and fibrinous bronchopneumonia?
Supprative- purulent or mucopurulent exudate confinded to lobules
Fibrinous- fibrinous exudate, spreads rapidly between lobules
What are some common causes of bronchopneumonia?
Bacteria- pasturalla multocida, bordatella bronchiseptica, truerella pyogenes, streptococcus, trueperella pyogenes, e.coli
Inhalation of bland material (milk)
Mycoplasmas- bovis, hyponeumoniae, dispae
Viruses
Describe the pathogenesis of bronchopneumonia?
- Inhaled agent- pathogen- causes injury at bronchiole-alveolar junction
- Exudation of fluid and plasma proteins, recruitment of alveolar macrophages and immigration of neutrophils
- Filling of alveoli and bronchioles with exudate, cells and debris
- Infection and inflammation spreads to adjecent lung then along airways to other lobules and interlobar septae if severe
Which of these two pictures is fibrinous and supprative bronchopneumonia?
A) Fibrinous
B) Supprative
What can cause fibrinous bronchopneumonia?
Bacteria- mannheima haemolytica in cattle
Inhalation of highly irritant material- Gastric HCl
Describe the pathogenesis of a mannheima haemoltyica infection in cattle
Shipping fever
Stress, viral infections and other factors impair respiratory defence mechanisms
M.haem colonisation of lower respiratory tract- laucotoxin production
Lysis of alveolar macrophages and neutrophils- releases lysosomal contents
Acute damage to blood vessels to fibrinous bronchopneumonia and toxaemia
What are the sequale of bronchopneumonia?
Resolution- natural or treatment
Chronic- BALT hyperplasia, goblet cell metaplasia
Bronchilitis obliterans
Bronchiectasis
Abscess formation
Pleuritis
Death
1) Where are the primary sites of injury in interstitial pneumonia?
2) What are the common causes?
3) What are the routes of entry?
4) Describe the distribution?
- Alveolar epithelium and capillary endothelium
- Viruses, bacteria, protozoa, helminths, irritants, allergy, toxins
- Inhalation, haematogenous
- Mainly diffuse, sometimes dorsocaudal
How can intersitial pneumonia be described macroscopically?
Can be diffucult to detect- no contract
Heavy rubbery or elastic texture, red, grey mottles
Often lack of visible exudate
Lungs often fail to collapse on opening of thorax, costal impression on pleural surface
Describe the 3 phases of interstitial pneumonia pathogenesis?
Injury- to type I pneumocytes or capillary endothelium, expansion of the interstitial tissue (oedema, inflammatory exudate)
Exudative phase- leakage of fluid and plasma protein in the alveolar space, may see hyaline membrane
Proliferative phase- macrophage population expands- phagocytose and remove exudate, type II pneumocytes proliferate to replace type I cells
What are the functional consequences of acute interstitial pneumonia?
Disruption of alveolat walls leads to hypoxia
What are some common causes of interstitial pneumonia?
Infections- viruses, septicaemic salmonellosis
Acute hypersensitivity reactions
Toxins- tryptophan- fog fever, paraquat
What happens when intersitial pneumonia is resolved?
Macrophages remove alveolar fluid and cells, type II pneumocytes convert to type I
What are some causes of chronic intersitial pneumonia?
Infections- ovine lentivirus
Hypersensitivity reactions
Toxins
Irritants
What chronic changes can occur if injury causing interstitial pneumonia persists?
Interstitial fibrosis
Chronic inflammatory cells
Persistence of type II pneumocytes
Smooth muscle hyperplasia
What are the consequences of chronic interstitial pneumonia?
Thickened alveolar walls
Decreased wall compliance
Increased respiratory effort- tachypnoea
Reduced airspace
Impaired diffusion
Reduced gas exchange- hypoxia
Obliterations of capillaries due to pressure- pulmonary hypertension
Hypoxia causes vascoconstriction adding to pulmonary hypertension
What two types of pneumonia are these images showing?
What happens to cause bronchointerstitial pneumonia?
Exudate fill interstitial tissue, bronchioles, bronchi and alveoli
Interstitial alveolar supprative exudate
Type II pneumocyte hyperplasia
What is the route of entry of embolic pneumonia?
Describe the distribution of embolic pneumonia
What are the common causes?
What are the potential sequelae?
ROE- haematogenous
Distribution- random disseminated foci
Common causes- hepatic abscesses, right heart valve endocarditis, joint/navel infections
Sequelae- formation of abseceses- could lead to fibrosis and resolution or chronic pneumonia or rupture- pyothorax/pneumothorax
Briefly describe what this image is showing?
This image shows lungs
The lungs have random disseminated rasied lesions yellow/orange in colour
Embolic pneumonia
What causes granulomatous pneumonia?
What are the routes of entry?
Describe the distribution of granulomatous pneumonia
Caused by agents that persist in tissues- induce chronic inflammation
ROE- inhaled, haematogenous
Distribution- variable, nodular foci
What are the different common causes of granulomatous pneumonia?
Bacterial- mycobacteria, actinobacillus, actinomyces, nocardia
Parasites- migrating parasites, lung worm, angiostrongylus vasorum
Viral- FIP
Fungi
Foreign bodies
What do these two images from the same animal show?
Top image shows a cattles lung with granulomatous pneumonia
Bottom image shows a slide stained with Zeihl-Neelson which shows acid fast bacteria revealing that this cow is infected with mycobacteria bovis (TB)
What different types of neoplasia can originate in the lung and what tissue is most common?
Carcinoma- bronchioloavleolar, squamous cell
Adenocarcionma- papillary, acinar
Chrondrosarcoma
Grannular cell tumour
Most primary originate from the epithelium
What is pulmonary adenomatotsis aka driving sickness?
Affects intensely housed sheep
Retro-viral induced neoplasia
Multicentric bronchioalveolar carcinoma
Cuboidal columnar cells resembling type II pneumocytes
How can pulmonary adenomatosis be identified in PM and in a clinical case?
PM- lungs are heavy with small grey to white nodules
Clinical case- wheel barrow test- mucoud fluid dribbles out
Why is metastatic neoplasia of the lung common?
What neoplasias are commonly metastatic in the lungs?
Good blood supply and fine capillary network
Mammary tumours, oestosarcoma, haemangiosarcoma
What are common causes of pneumothorax?
Spontaneous rupture of abscesses, emphysematous bulla
Traumatic rupture or perforation of lung/trachea
Penetrating injury of thoracic wall
What diseases affectthe pleural cavity?
Pneumothorax
Circulatory diseases- effusions
Pleuritis- inflammatory conditions
Neoplasia
What different pleural effusions are common?
What do they all cause and why?
Hydrothorax-oedema fluid
Haemothorax- blood
Cylothorax-lymph
Pyothorax- pus
1) What are common causes of hydrothorax?
2) What are common causes of haemothorax?
3) What are common causes of chylothorax?
4) What are common causes of pyothorax?
1) Oedema/transudate in the pleural space:
Heart failure
Hypoproteinaemia
Intrathoracic tumours
2) trauma and rupture of blood vessels
erosion of blood vessles
clotting disorders (Doberman with Von willebrands)
3) traumatic rupture or neoplastic erosion of the thoracic duct wall
congenital anomaly
heart disease
4) penetrating injury, lung abscess rupture
How is pleuritis classified?
Fibrinous
Supprative
Granulomatous
What can be the problem with chronic pleuritis?
Adhesions of fibrin reduces compliance of the lungs
What are causes of pleuritis?
Pneumonia
Bacteraemia
Pyothorax
FIP virus
What are the three neoplasias of the pleural cavity?
Primary
Mediastinal
Metastases
Whats an example of a primary neoplasia of the pleural cavity and what are the risk factors?
Mesothelioma
Asbestos or spontaneous
Boviers, irish setters, german shepards
More in males
What are some examples of mediastinal tumours of the pleural cavity?
Thymoma
Lymphoma
